WO2018088628A1 - Styrene-butadiene rubber compound and rubber composition comprising same for tire bead filler - Google Patents

Abstract

The present invention relates to a styrene-butadiene rubber compound and a rubber composition comprising the same for a tire bead filler and, more specifically, to a styrene-butadiene rubber compound capable of enhancing rigidity and hardness even though styrene-butadiene rubbers having different styrene contents are used in substitution for a combination of a natural rubber and a phenol-based resin in the conventional art, and to a rubber composition comprising the same for a tire bead filler.

Description

Styrene-butadiene rubber compound and rubber composition for tire bead filler comprising the same

This application claims the benefit of priority based on Korean Patent Application No. 10-2016-0149391 dated November 10, 2016, and all content disclosed in the literature of that Korean patent application is incorporated as part of this specification.

The present invention relates to a styrene-butadiene rubber compound having excellent rigidity and hardness and a rubber composition for a tire bead filler comprising the same.

Tire bead filler rubber requires higher stiffness and hardness than other parts of the rubber compound to support the load of the vehicle delivered to the rim when the rim is mounted on the tire, and prevents bead separation that may occur when driving the vehicle. High rubber stiffness is required to achieve this.

In order to improve the rigidity of the tire bead filler rubber, a method of increasing the hardness and rigidity of the rubber by increasing the content of an inorganic material such as clay is used. However, if the clay content is high, the rubber hardness increases, but heat generation between clay and rubber increases, thereby reducing rolling resistance, deteriorating rubber compounding properties, and lowering tensile strength. In addition, clays conventionally used have a low oil adsorption amount and a low reinforcing effect on the rubber composition.

In addition, as another method for improving the rigidity of tire bead filler rubber, a method of improving the rigidity and hardness using a phenolic resin of novolak type or a modified phenolic resin has been proposed. This method has the advantage of improving rigidity and hardness, but has the disadvantage that the rigidity of the rubber also decreases as the rigidity of the resin decreases at a high temperature, which is a driving condition after tire mounting.

As an alternative, Korean Patent Publication No. 2011-0071605 uses two kinds of carbon blacks having different physical properties for raw rubber, and in 2016-0077895, thermoplastic elastomer is used for raw rubber to improve the rigidity of the rubber. Promoted. These methods showed some improvement in stiffness but did not yield satisfactory results. In particular, in the above patent, due to the low compatibility with the synthetic rubber added with the natural rubber as a rubber composition, the hardness of the final bead filler also could not be sufficiently secured.

[Preceding technical literature]

[Patent Documents]

Republic of Korea Patent Publication No. 1998-0009357 (1998.04.30), rubber composition for the bead filler of the tire

Republic of Korea Patent Publication No. 2011-0071605 (June 29, 2011), the rubber composition for the tire bead filler and a tire manufactured using the same

Republic of Korea Patent Publication No. 2016-0077895 (2016.07.04), the rubber composition for the tire bead filler and a tire manufactured using the same

Therefore, the present inventors conducted a study to increase the hardness and rigidity with only synthetic rubber when manufacturing the tire bead filler, when the styrene-butadiene rubber mixed with different styrene content is used to improve the hardness and rigidity of the natural rubber and phenol The present invention was completed by confirming that it could be used as an alternative to the resin.

Accordingly, it is an object of the present invention to provide a rubber composition for tire bead filler having high hardness and rigidity.

In order to achieve the above object, the present invention

a) first styrene-butadiene rubber having a styrene content of 60 to 95% by weight, a particle size of 100 to 200 nm, and a Mooney viscosity difference (ΔMV) of 3 to 7 before and after blending; And

b) a styrene-butadiene rubber compound, characterized in that it comprises a second styrene-butadiene rubber having a styrene content of 5 to 10% by weight.

The present invention also provides a rubber bead filler rubber composition comprising a styrene-butadiene rubber compound as described above in the composition for a tire bead filler comprising a rubber, a reinforcing agent and an additive.

The rubber composition proposed in the present invention excludes resins such as phenolic resins, which have conventional rigidity problems, and is possible to substitute natural rubber and phenolic resins, thereby enabling the production of tires made of only synthetic rubber.

The present invention provides a compound and a composition for a tire bead filler including the same, which can improve physical properties such as strength and stiffness using only synthetic rubber without using natural rubber and phenolic resin used in tire bead filler manufacturing.

Styrene-butadiene rubber consists of styrene repeating units and butadiene repeating units.

The standard styrene-butadiene rubber has a total styrene content of 23.5% by weight in butadiene rubber, the higher styrene content is called high styrene-butadiene rubber, and the lower styrene content is low styrene. -It is called low styrene butadiene rubber.

Compounds presented in the present invention have different styrene contents, that is, high styrene-butadiene rubber (hereinafter referred to as 'first styrene-butadiene rubber') and low styrene-butadiene rubber (hereinafter referred to as 'second styrene-butadiene rubber' To be used). Conventionally, the formulation of styrene-butadiene rubber having different styrene contents is not easy, but in the present invention, the first styrene-butadiene rubber having a high styrene content is used in which particle size and Mooney viscosity are controlled. The low second styrene-butadiene rubber uses a controlled polymerization process, and has excellent thermal stability after blending, and improves workability and adhesion during processing, thereby improving physical properties, particularly stiffness (tensile strength) and hardness. It allows for the production of improved molded articles.

Hereinafter, each styrene-butadiene rubber will be described in detail.

First styrene-butadiene rubber

The first styrene-butadiene rubber as the first component of the rubber composition according to the present invention has a styrene content of 60 to 95% by weight, preferably 80 to 90% by weight, as mentioned above, and has a crosslinked structure. Have

Although the use of styrene-butadiene rubbers with different styrene contents can theoretically secure a complementary effect on physical properties, it has various problems when applied to the actual process due to its low miscibility. However, the first styrene-butadiene rubber of the present invention has a particle size of 100 to 200 nm, and a Mooney viscosity (ML _{(1 + 4)} at and before and after blending _). The miscibility between these can be improved by using the thing (DELTA MV) of 100 degreeC) 3-7.

The particle size of the first styrene-butadiene rubber can be measured by a device used for measuring a conventional latex particle size, wherein the average particle diameter has the above range, that is, 100 to 200 nm, preferably 120 to 180 nm. If it falls within the particle size range, the miscibility with the second styrene-butadiene rubber may be increased, and the improvement effect of the stiffness and hardness obtained through the mixed use thereof may be expected. If the particle size is too small, agglomeration may occur between the particles to form a uniform blend with the second styrene-butadiene rubber, and if too large, the desired level of rigidity and hardness specification may not be achieved.

In addition, the 1st styrene-butadiene rubber of this invention uses the thing in which the difference of the Mooney viscosity before mix | blending and the Mooney viscosity after mix | blending has a predetermined range.

Mooney Viscosity is a measure of the viscosity of a rubber or rubber compound (or compound) with temperature. The measurement conditions are expressed in ML _{1 + 4} (at 100 ° C), where ML is the size of the rotor (LARGE, 1). +4 is the time for warming up the specimen at the specified temperature, 1 minute, 4 minutes for measurement, and 100 ° C for the measured temperature. In other words, Mooney viscosity expresses numerically how much force at what temperature and time. In this case, the Mooney viscosity of 3 means preheating 1 minute using a Large Disc at a temperature of 100 ℃, and means that the viscosity resin measured after 4 minutes is 3.

The first styrene-butadiene rubber is difficult to measure the gel content unlike the second styrene-butadiene rubber having a linear structure in a crosslinked form. Such gel content can be predicted through a change in Mooney viscosity before and after blending, and preferably, a Mooney viscosity difference (ΔMV) before and after blending is 3 to 7, preferably 3 to 6.7, by ASTM standard formulation method.

As set forth above, the first styrene-butadiene rubber according to the present invention uses one in which the average particle diameter and the Mooney viscosity are simultaneously defined. If the average particle diameter as the first styrene-butadiene rubber satisfies the above range, when the Mooney viscosity difference exceeds the above range, the stiffness and hardness are lowered, and the Mooney viscosity difference satisfies the above range, but the average particle diameter falls outside the above range. This also causes a problem that the rigidity and hardness are lowered.

In addition, the first styrene-butadiene rubber of the present invention has a weight average molecular weight of 100,000 g / mol to 2,000,000 g / mol, specifically 300,000 g / mol to 2,000,000 g / mol, more specifically 500,000 g / mol to 2,000,000 g / mol is used.

On the other hand, the first styrene-butadiene rubber proposed in the present invention is a crosslinked styrene and butadiene is prepared through emulsion polymerization.

The first styrene-butadiene rubber usually has a form crosslinked by a crosslinking agent and has a high level of gel content. The first styrene-butadiene rubber of the present invention is crosslinked with only styrene and butadiene as monomers without using a crosslinking agent. In this case, the crosslinking is performed through the control of the polymerization reaction temperature and the polymerization conversion rate. When crosslinking is performed without a crosslinking agent as described above, the content of styrene can be further increased, and the crosslinking content and density control can be easily performed through the use of a molecular weight modifier.

Specifically, the preparation of the first styrene-butadiene rubber may be prepared by emulsion polymerization by adding an emulsifier, an initiator, and a molecular weight modifier to the styrene and butadiene monomers.

The monomer is used in 80 to 95% by weight of styrene and 5 to 20% by weight of butadiene within 100% by weight of the total monomer, it is possible to manufacture a rubber with a high content of styrene within these ranges.

The styrene may be, in addition to styrene, further α-methyl styrene, o-methyl styrene, p-methyl styrene, m-methyl styrene, ethyl styrene, i-butyl styrene, t-butyl styrene or alkyl styrene having equivalent properties; And at least one selected from the group consisting of o-bromo styrene, p-bromo styrene, m-bromo styrene, o-chloro styrene, p-chloro styrene, m-chloro styrene or halogenated styrene having equivalent properties. Can be.

In addition, butadiene may impart flexibility to the styrene-butadiene-based latex, and may act as a crosslinking agent, and may be 1,3-butadiene, 1,4-butadiene, 2,3-dimethyl-1,3-butadiene, or 2 Butadiene or derivatives thereof, such as -ethyl-1,3-butadiene, and the like; in addition to these, 2-methyl-1,3-pentadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, It may further include a conjugated diene monomer such as 4-methyl-1,3-pentadiene, 1,3-hexadiene or 2,4-hexadiene.

In this case, the styrene and butadiene monomers are introduced in a method of introducing the monomer mixture into the polymerization reactor at once, a method of continuously adding the monomer mixture into the polymerization reactor, a part of the monomer mixture is introduced into the polymerization reactor, and the remaining monomers are continuously added to the polymerization reactor. You may use any of the methods of supplying by a.

The emulsifier is not particularly limited in the present invention, it is possible to use commonly in this field. For example, as the emulsifier, known ones such as phosphate type, carboxylate type, sulfate type, succinate type, sulfosuccinate type, sulfonate type, and disulfonate type can be used, and the present invention is not particularly limited. Do not. As one example, one or a combination of two or more selected from the group consisting of alkyl aryl sulfonates, alkali methyl alkyl sulfates, sulfonated alkyl esters, soaps of fatty acids and alkali salts of rosin acids can be used.

Such emulsifiers are used in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the total monomers. If the content is less than the above range, the stability during polymerization is lowered. On the contrary, if the content exceeds the above range, foaming increases.

The molecular weight modifier is not particularly limited, but for example, mercaptans such as a-methylstyrene dimer, t-dodecylmercaptan, n-dodecylmercaptan, octyl mercaptan, halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide, tetra Sulfur-containing compounds such as ethyl thiuram disulfide, dipentamethylene thiuram disulfide, diisopropylquixanthogen di sulfide. Preferably t-dodecyl mercaptan.

In addition, the molecular weight regulator may be added in an amount of 0.2 to 0.6 parts by weight based on 100 parts by weight of the total monomers, but is not limited thereto.

The polymerization initiator may control the molecular weight, gel content and gel structure of the first styrene-butadiene rubber, and is not particularly limited, but a radical initiator may be used. As said radical initiator, inorganic peroxides, such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-mentane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide Organic peroxides such as oxides, 3,5,5-trimethylhexanol peroxide, t-butyl peroxy isobutyrate; At least one selected from the group consisting of azobis isobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexane carbonitrile, and azobis isobutyric acid (butyl acid) methyl, and among these radical initiators Inorganic peroxide is more preferable, and persulfate can be used preferably.

The amount of the polymerization initiator is included in an amount of 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of the total monomers. If the content is less than the above range, the polymerization rate is lowered, making it difficult to manufacture the final product. On the contrary, if the content exceeds the above range, the polymerization rate is too fast to control the polymerization.

At this time, in addition to the above composition, if necessary, additives such as a molecular weight regulator, an activator, a chelating agent, a dispersing agent, a pH adjusting agent, a deoxygenating agent, a particle size adjusting agent, an antioxidant, and an oxygen scavenger may be added.

As mentioned above, the first styrene-butadiene rubber proposed in the present invention may perform crosslinking without a crosslinking agent by controlling the polymerization temperature and the polymerization conversion rate.

When rubber is manufactured, it is called high temperature rubber (or hot polymer) that performs polymerization temperature at 40 ℃ or higher, and rubber with high gel content and excellent processability is obtained. Or cold polymer).

In the present invention, the polymerization is carried out at a high temperature, preferably at a high temperature of 40 to 80 ℃, preferably 45 to 75 ℃, the polymerization is terminated after the polymerization conversion reaches 90% or more.

After completion of the polymerization, the first styrene-butadiene rubber prepared in latex form is obtained in a powder state by performing a conventional post-treatment procedure such as solidification and washing.

Coagulation is carried out through the addition of coagulants, wherein coagulants are such as barium chloride, calcium chloride, magnesium chloride, zinc chloride and aluminum chloride; metal chlorides; Nitrates such as barium nitrate, calcium nitrate and zinc nitrate; Acetates such as barium acetate, calcium acetate and zinc acetate; Sulfates such as calcium sulfate, magnesium sulfate, and aluminum sulfate. Of these, calcium chloride and magnesium sulfate are preferred. The coagulation may be coagulation at 50 to 100 ° C., and coagulation agent may be 5 wt% or less based on the total amount of the total salt used for coagulation.

The washing can be carried out at 50 to 90 ° C. through the use of distilled water or the like.

Styrene-butadiene rubber

In addition, the second styrene-butadiene rubber, which is the second component of the rubber composition according to the present invention, is a rubber having a linear structure having a styrene content of 1 to 15% by weight, preferably 5 to 10% by weight.

The second styrene-butadiene rubber is prepared by emulsion polymerization, but is prepared by emulsion polymerization at low temperature using a mixture of aliphatic organic acids and sulfonate compounds.

First, a monomer, an emulsifier, a polymerization initiator, a molecular weight regulator, and deionized water are added to a polymerization reactor.

As the monomer, styrene and butadiene are used. In this case, styrene is used in 1 to 15% by weight, preferably 5 to 10% by weight, and butadiene is used in 85 to 99% by weight, preferably 90 to 95% by weight within 100% by weight of the total monomers. If the content is outside the third range, it is difficult to prepare low styrene-butadiene rubber having a desired level of physical properties.

In particular, the second styrene-butadiene rubber of the present invention is prepared by using a specific emulsifier used in emulsion polymerization and carrying out polymerization at low temperature.

As the emulsifier, an aliphatic organic acid and a sulfonate compound are used together.

The aliphatic organic acid may be, for example, an aliphatic organic acid having 12 to 18 carbon atoms, or may be an aliphatic organic acid having 14 to 18 carbon atoms or 16 to 18 carbon atoms. Specific examples include oleic acid, lauric acid, myristic acid, myristic acid, palmitic acid, stearic acid, naphthalene sulfonic acid, and eicosanoic acid. One or more selected from among them can be used.

The sulfonate compound includes one selected from the group consisting of alkyl aryl sulfonates, alkali methyl alkyl sulfates, sulfonated alkyl esters, alkali salts of rosin acids, naphthalene sulfonic acids, and combinations thereof. SANS uses Sodium 1- (n-Alkyl-Naphthalene-4-Sulfonate) and SDBS (Sodium Dodecyl Benzene Sulfonate), but is not limited thereto.

Such sulfonate compounds are used in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the total monomers. If the content is less than the above range, the stability during polymerization is lowered. On the contrary, if the content exceeds the above range, foaming increases.

In addition, the aliphatic organic acid and the sulfonate compound are used in a weight ratio of 1: 1 to 10: 1. If an excessive amount of aliphatic organic acid is used, there is a problem that the coagulum in the produced second styrene-butadiene rubber latex increases, and an excessive use of a sulfonate compound causes a long polymerization time, so it is appropriately used within the above range. do.

In this case, the polymerization initiator, the reaction terminator, and the like used together follow the description of the first styrene-butadiene rubber.

However, in the emulsion polymerization in relation to the polymerization temperature, the polymerization temperature may be performed at a low temperature of 5 to 20 ° C., preferably 5 to 15 ° C., and may be performed so that the required time for reaching the polymerization conversion rate of 80% is 7 to 8 hours. have. This time is a time reduced by 1 to 2 hours or more as compared with the usual required time, which can shorten the overall reaction process time.

The completion of the polymerization usually terminates the polymerization at a polymerization conversion rate of 80% to obtain a second styrene-butadiene rubber in latex form.

The second styrene-butadiene rubber thus prepared has a weight average molecular weight of 10,000 g / mol to 2,000,000 g / mol, specifically 100,000 g / mol to 1,000,000 g / mol, more specifically 150,000 g / mol to 800,000 g / mol I use that.

The first styrene-butadiene rubber and the second styrene-butadiene rubber as described above are combined with each other to produce a compound.

In this case, the compound includes 75 to 99.5% by weight of the first styrene-butadiene rubber, preferably 80 to 95% by weight so that the total amount is 100% by weight, and 0.5 to 25% by weight of the second styrene-butadiene rubber, preferably 5 to When it contains 20% by weight, it is possible to secure high rigidity and hardness.

If the content of the first styrene-butadiene rubber is less than the above range or the content of the second styrene-butadiene rubber is more than the above range, sufficient level of rigidity and hardness may not be secured, on the contrary, the first styrene-butadiene When the content of the rubber exceeds the above range or the content of the second styrene-butadiene rubber below the above range, the modulus and elastic properties are lowered, so it is suitably used within the above range.

The total styrene content of the styrene-butadiene rubber compound according to the invention as described above is 23 ± 2% by weight and the Mooney viscosity (ML _{(1 + 4)} / 100 ° C.) has 46 ± 3. Such compounds are applicable to a variety of technical fields, and may be particularly preferably applied to the production of bead fillers for tires.

Tire bead fillers are required to support the load of the vehicle being transferred to the tire rim and require high rigidity and hardness. In general, the tire bead filler is a natural rubber, phenol resin, carbon black, and additives as a basic component, when using the styrene-butadiene compound proposed in the present invention can be used in place of the natural rubber and phenol resin.

Conventionally, a technique of using styrene-butadiene rubber as an additional rubber component to natural rubber is known, but in the present invention, the production of tire bead fillers is possible using only natural rubber by blocking natural rubber.

The performance of the bead fillers depends on the macrostructures of styrene-butadiene rubber (molecular weight, molecular weight distribution, macromolecular chains, crystallinity, etc.) and microstructures (array of monomers, polystyrene content, polydiene content, vinyl content), and chemical functionalization. It is greatly affected. That is, the glass transition temperature (Tg) increases, the tensile strength decreases, and the wear resistance decreases, but the wet road braking force tends to increase according to the styrene content.

Thus, by using a compound in which styrene different rubbers are formulated in a certain ratio, the rigidity and hardness required for the bead filler are sufficiently secured.

The remaining components of the rubber composition constituting the tire bead filler, carbon black, reinforcing agents such as silica, vulcanizing agents, vulcanizing accelerators, processing oils, fillers, coupling agents, antioxidants, softeners or adhesives may be further included. have.

Sulfur is used as a vulcanizing agent, and peroxide-based compounds may be used in addition, but sulfur crosslinking systems are generally used.

The vulcanization accelerator serves to improve the vulcanization efficiency and reaction rate by allowing the vulcanization reaction to occur uniformly at the rubber reaction site. The vulcanizing accelerator may be at least one selected from the group consisting of thiazole-based, thiuram-based, thiourea-based, guanine-based and thiocarbamate-based activators. have. Specific examples of the thiazole type include N-t-butyl-2-benzothiazole sulfenamide (TBBS).

The processing oil acts as a softener in the rubber composition, specifically, may be a paraffinic, naphthenic, or aromatic compound, and more specifically, aromatic process oil, hysteresis loss and low temperature in consideration of tensile strength and wear resistance. In consideration of properties, naphthenic or paraffinic process oils may be used. The processing oil may be included in an amount of 100 parts by weight or less based on 100 parts by weight of compound, and when included in the content, it is possible to prevent the degradation of tensile strength, low heat generation (low fuel efficiency) of the vulcanized rubber.

Specific examples of the anti-aging agent include N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 6-ethoxy- And 2,2,4-trimethyl-1,2-dihydroquinoline or high-temperature condensates of diphenylamine and acetone. The anti-aging agent may be used in an amount of 0.1 parts by weight to 6 parts by weight based on 100 parts by weight of the compound.

The rubber composition according to an embodiment of the present invention can be obtained by kneading using a kneading machine such as a Banbury mixer, a roll, an internal mixer, etc. by the above formulation, and also has low heat resistance and abrasion resistance by a vulcanization process after molding. This excellent rubber composition can be obtained.

The rubber molded article manufactured by such a composition and method is applied to a bead filler of a tire, in particular a tire, wherein the tire may be an automobile tire, a bus tire, a truck tire, an airplane tire, a motorcycle tire, and the like.

Hereinafter, preferred examples are provided to help the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and various changes and modifications within the scope and spirit of the present invention are apparent to those skilled in the art. It goes without saying that changes and modifications belong to the appended claims.

EXAMPLE

Example  One

(1) Preparation of First Styrene-Butadiene Rubber

1.2 parts by weight of potassium rosin salt, 1.5 parts by weight of potassium oleate salt, 0.05 parts by weight of dodecyl mercaptan, cumene hydride, based on 100 parts by weight of a monomer composed of 12 parts by weight of 1,4-butadiene and 88 parts by weight of styrene in the reaction vessel 0.5 parts by weight of loperoxide and 200 parts by weight of water were added thereto, and prepared by emulsion polymerization at 10 ° C. The completion of the reaction was completed at the time of 90% polymerization conversion.

2 parts by weight of calcium chloride was added to 100 parts by weight (solid content) of the obtained first styrene-butadiene rubber latex, heated to 70 ° C., aged for 20 minutes, cooled to obtain a coagulated product, and washed with ion-exchanged water two or three times to retain residual monomer. After removal, it was dehydrated using a filter. It was then dried using a roll dryer to produce a high styrene-butadiene rubber.

The particles of the prepared first styrene-butadiene rubber were measured using a particle size analyzer, and the average particle diameter was measured to be 120 nm.

(2) Preparation of Second Styrene-Butadiene Rubber

3.5 parts by weight of an aliphatic organic acid (Fatty acid (company name: LG Household & Health, Co., Ltd., elofad TP 200), SANS (100 parts by weight of 94 parts by weight of 1,4-butadiene and 6 parts by weight of styrene) in the reaction vessel 0.5 part by weight of sodium 1- (n-Alkyl-Naphthalene-4-Sulfonate), 0.05 part by weight of dodecylmercaptan, 0.5 part by weight of cumene hydroperoxide, and 200 parts by weight of water were added to prepare the product through emulsion polymerization at 10 ° C. The termination was completed at the time of 80% polymerization conversion.

Particles of the prepared second styrene-butadiene rubber were measured using a particle size analyzer, and the average particle diameter was measured to be 250 nm.

(3) Compound  Produce

After latex blending the first styrene-butadiene rubber and the second styrene-butadiene rubber obtained in (1) and (2) to an 8: 2 weight ratio, 2 parts by weight of calcium chloride was added to 100 parts by weight (solid content) of the blended latex. The mixture was warmed to 70 ° C., aged for 20 minutes, cooled to obtain a coagulum, washed 2-3 times with ion-exchanged water to remove residual monomer, and then dehydrated using a filter. Subsequently, it dried using the roll dryer and manufactured the compound of the coagulated | solidified state.

The prepared styrene-butadiene rubber coagulum was blended according to ASTM D3187 using a Bunbury mixer to prepare a specimen.

Example  2

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 140 nm was prepared and used.

Example  3

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 180 nm was prepared and used.

Comparative example  One

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 80 nm was prepared and used.

Comparative example  2

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 90 nm was prepared and used.

Comparative example  3

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 100 nm was prepared and used.

Comparative example  4

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 130 nm was prepared and used.

Comparative example  5

A rubber compound specimen was prepared in the same manner as in Example 1 except that the first styrene-butadiene rubber having an average particle diameter of 210 nm was prepared and used.

	Content ratio (weight)	First styrene-butadiene rubber
	1st styrene-butadiene rubber / 2nd styrene-butadiene rubber	Particle size (nm)	Mooney Viscosity Difference After Compounding (△ MV)
Example 1	8: 2	120	6.7
Example 2	8: 2	140	5.0
Example 3	8: 2	180	3.0
Comparative Example 1	8: 2	80	5.0
Comparative Example 2	8: 2	90	6.0
Comparative Example 3	8: 2	100	8.0
Comparative Example 4	8: 2	130	2.5
Comparative Example 5	8: 2	210	5.0

Experimental Example  One

The physical properties of the rubber specimens prepared in Examples and Comparative Examples were measured based on the following, and the results are shown in Table 2 below.

(One) Compound  characteristic

* MV (Mooney viscosity): measured according to DIN 53523/3.

* Formulation Thermal Stability Evaluation Condition

Milling work with 0.2mm thickness (200g sample) on 160 ℃ roller and sampled Aging specimen at 1.5, 5, 10, 15, 20, 25, 30, 40, 50, 60 minutes intervals It was. Evaluation was made with the 5-point method, and the lower the score in 0-5 points | pieces means that compounding thermal stability fell.

(2) Vulcanization characteristics (MDR: Moving DieRheometer )>:

The vulcanization profile and its related analytical data were measured on a Monsanto MDR2000 rheometer according to ASTM D5289-95.

* T5: Time required until 5% vulcanization was measured (160 ° C., 3 minutes).

* Vmax (vulcanization speed): It means the maximum torque required for 100% vulcanization.

(3) mechanical properties

Tensile strength (TS: kgf / cm ² ): The compound was vulcanized at 145 ° C. for 45 minutes, and then the tensile strength of the 300% vulcanizate was measured.

Elongation (%): After elongation of the compound at 145 ° C for 45 minutes, the elongation of the vulcanizate was measured.

100% Modulus (kgf / cm ² ): The compound was vulcanized at 145 ° C. for 45 minutes, and then the modulus at 100% elongation was measured.

* Hardness: Durometer hardness (JIS A, Shore type) was used according to ASTM D2240 to measure the hardness of the prepared vulcanizate. The thickness of the vulcanized sample was made to be at least 6 mm so that the needle was perpendicular to the measurement surface of the test piece, and the average value was determined after measuring three times at the center of the test piece with a load of about 2 kg (19.6 N).

		Example 1	Example 2	Example 3	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5
Rubber Compound Properties	MV	47	46	45	47	45	43	46	41
	Compound thermal stability (5-point method)	39.1	38.2	39.2	41.2	42.0	43.2	40.0	39.9
MDR (160 ℃, 30min)	T5 (min)	1.31	1.34	1.39	1.08	1.13	1.2	1.32	1.4
	Vmax (N.M)	24.7	25.1	25.9	21.2	22.1	26.2	21.8	24.1
Mechanical properties	Tensile strength (kgf / cm 2 )	187	185	193	171	156	167	156	178
	% Elongation	332	374	347	298	275	277	374	362
	100% Modulus (kgf / cm 2 )	59	51	56	48	52	55	45	45
	Hardness	80	79	78	78	77	77	76	75

Referring to Table 2, in the case of the rubber compound using the first styrene-butadiene rubber of the embodiment of which the particle size and the Mooney viscosity is limited according to the present invention, the physical properties compared to the compound of the comparative example showed more than equivalent results, in particular stiffness and The results showed that the hardness is greatly improved.

Specifically, when the first styrene-butadiene rubber particles are too small, as in Comparative Examples 1 and 2, the overall physical properties were low. Moreover, when the average particle diameter was large like the comparative example 5, the elongation characteristic became high but the rigidity and hardness were shown to fall rather similarly. In addition, in the case of Comparative Examples 3 and 4, the average particle diameter corresponds to the present invention, but when the Mooney viscosity is high or low, all of the stiffness, elongation, modulus, and hardness showed low results compared to the compounds of Examples 1 to 3.

The rubber compound and the bead filler prepared using the present invention can be applied to various tires such as automobile tires, bus tires, truck tires, aircraft tires, motorcycle tires.

Claims (10)

1. a) first styrene-butadiene rubber having a styrene content of 60 to 95% by weight, a particle size of 100 to 200 nm, and a Mooney viscosity difference (ΔMV) of 3 to 7 before and after blending; And

   b) a styrene-butadiene rubber compound, characterized in that it comprises a second styrene-butadiene rubber having a styrene content of 5 to 10% by weight.
2. The method of claim 1,

   Styrene-butadiene rubber compound, characterized in that the rubber compound comprises 75 to 99.5% by weight of the first styrene-butadiene rubber and 0.5 to 25% by weight of the second styrene-butadiene rubber.
3. The method of claim 1,

   Styrene-butadiene rubber compound, characterized in that the total styrene content of the styrene-butadiene rubber compound is 23 ± 2% by weight, the Mooney viscosity (ML _{(1 + 4)} / 100 ℃) is 46 ± 3.
4. The method of claim 1,

   The styrene-butadiene rubber compound has a weight average molecular weight of 1,000 g / mol to 2,000,000 g / mol.
5. The method of claim 1,

   The styrene-butadiene rubber compound has a weight average molecular weight of 1,000 g / mol to 2,000,000 g / mol.
6. The method of claim 1,

   The styrene-butadiene rubber compound is characterized in that the first styrene-butadiene rubber and the second styrene-butadiene rubber are prepared through emulsion polymerization.
7. The method of claim 1,

   The second styrene-butadiene rubber is a styrene-butadiene rubber compound, characterized in that prepared using an aliphatic organic acid and sulfonate compound as an emulsifier.
8. In the composition for tire bead filler containing rubber, reinforcing agent and additives,

   The rubber composition for a tire bead filler comprising a styrene-butadiene rubber compound according to any one of claims 1 to 7.
9. The method of claim 8,

   The reinforcing agent rubber composition for a tire bead filler, characterized in that containing carbon black and silica.
10. The method of claim 8,

    The additive is a rubber composition for tire bead fillers, characterized in that at least one selected from the group consisting of vulcanizing agents, vulcanization accelerators, processing oils, fillers, coupling agents, anti-aging agents, softeners and pressure-sensitive adhesives.